The invention concerns a manufacturing process for laminated cards, and cards obtained by means of a process of this type.
The cards according to the invention are chip cards comprising a plastic card body, and an electronic module integrated in said card body, comprising an integrated circuit the contact pads of which are connected to other pads flush with the surface of the card body and/or the terminals of an antenna embodied in said card body.
Cards of this type are principally designed for processing or storing confidential data, for example for the purpose of executing electronic transactions in a variety of domains such as health care, pay TV, telephony and banking.
Cards of this type are generally personalized in -such a way as to identify their holders, and consequently carry printed marks for this purpose.
Various processes are known for the manufacture of cards. Some processes involve hot lamination. According to these processes, the different layers forming the body of the card are assembled at given pressures and temperatures, such that the plastic materials used in their manufacture reach their setting point, and inter-penetrate locally to create largely coherent laminated assemblies. These assemblies are then printed and cut to the required dimensions for a card body. A cavity is then milled in each body, and an electronic module is finally inserted and bonded in said cavity.
In these processes, the known materials used in the construction of the various layers are acrylonitrile butadiene styrene (ABS), polyvinyl chloride (PVC), ABS/PVC mixtures, polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG) and polycarbonate (PC). Frequently the various layers constituting the card body are of the same chemical nature, for example, all in PVC. In particular, the various superimposed layers in known PETG cards are all in PETG.
The manufacturing processes for state of the art cards, and cards obtained using processes of this type, nevertheless present a number of drawbacks.
In particular, cards in ABS, PVC, ABS/PVC mixtures, PET and PC show limited resistance to dynamic, longitudinal and lateral bending. In general, they crack after about 1,500 dynamic longitudinal bends, with a 20 mm deflection centered on the card body, and about 1,500 lateral dynamic bends with a 10 mm centered deflection.
However, this is not the case with cards in PETG, which on the contrary, show good resistance to the above bending loads. Nevertheless, given the low viscosity of PETG at normal laminating temperature and pressure conditions, it is necessary to reduce laminating temperatures at a given pressure, to avoid all the drawbacks of PETG creep in the laminating equipment. However, at these reduced temperatures, the coherence of the laminated assemblies obtained is found to be mediocre, and it is difficult in practice to find a compromise which makes it possible to avoid both PETG creep problems and the coherence drawbacks of said laminated assemblies at the same time.
The invention concerns a contact-free chip card, comprising a card body incorporating an antenna coupled to an electronic circuit. The card body comprises two outer layers and one intermediate layer placed between the two outer layers. The intermediate layer incorporates the antenna and electronic circuit. Each outer layer is connected to the intermediate layer via a bonding layer, for which the melting point is below that of said outer layers.
In view of the foregoing, a problem which the invention proposes to solve is the manufacture of a card with, on the one hand, a card body incorporating at least three laminated plastic layers directly superimposed on each other, with the second layer placed between the first and third layers, and an electronic module incorporated in said card body, said module comprising an integrated circuit, said card showing good resistance to dynamic bending, and for the manufacture of which the problems of creep and coherence are satisfactorily overcome.
Considering the above-mentioned problem, the first objective of the solution proposed by the invention is a manufacturing process for a card of this type, characterized by the fact that the second layer being a layer in polyethylene terephthalate glycol, and the first and third layers being of a different nature to said second layer,xe2x80x94the first, second and third layers are laminated so as to obtain a first laminated assembly,xe2x80x94a cavity is executed in the second layer,xe2x80x94and the module is inserted in said cavity.
In this way, the PETG is contained between the first and third layers, and does not creep during lamination.
The resultant card also has good coherence, the plastic materials of the three layers having reached their setting point, and the resistance of said card to dynamic bending is better than that for state of the art cards.
The process according to the invention has the advantage of including a subsequent step wherebyxe2x80x94said first laminated assembly, in which the module has been inserted, is laminated under temperature and pressure conditions such that the PETG reaches its setting point so that a second laminated assembly is obtained.
The PETG, which has low viscosity under the conditions defined above, then fills the space between the edges of the cavity and the edges of said module, thus ensuring that the module is held firmly in place in the card body.
Another advantage resulting from this step appears when the second lamination, using an operating method particular to the invention, is executed in the presence of a fourth plastic layer. This plastic layer does not undergo the strains normally encountered.
It should be noted that the second objective of the invention is to obtain a card characterized by the fact that said second layer is a layer of polyethylene terephthalate glycol, and that the first and third layers are of a chemical nature different from that of said second layer.